ETFE is excellent in heat resistance, flame retardancy, chemical resistance, weather resistance, a low friction property and a low dielectric characteristic, and is used in a wide range of fields, such as coating materials for heat resistant flame retarding electric wires, corrosion resistant piping materials for chemical plants, agricultural vinyl house materials, and release coating materials for kitchen utensils. However, since the intermolecular cohesion is weak, the affinity to other materials is poor, and there has been a problem such that a polymer alloy having excellent properties can hardly be obtained.
In order to improve the compatibility of the fluorine-containing copolymer and a polyolefin, a method of using a polyolefin as alkyl acrylate-modified (JP-B-4-73459), or a method of incorporating carboxyl groups, hydroxyl groups or epoxy groups to a fluorine-containing polymer (JP-A-62-57448), has been proposed.
The former is effective in a case where the fluorine-containing polymer is a vinylidene fluoride type polymer or a vinyl fluoride type polymer having a high polarity, but in the case of ETFE having a low polarity, the compatibility can not be improved.
Whereas, the latter may, for example, be (1) a method wherein a fluorine-containing polymer and a non-fluorine type thermoplastic polymer having functional groups are blended, (2) a method wherein, in the synthesis of a fluorine-containing polymer, polymer units based on the polymerization of a polymerizable monomer having a functional group, are incorporated, (3) a method wherein the reactive groups present in a fluorine-containing polymer are reacted with a compound having a functional group or a compound capable of forming a functional group by the reaction, or (4) a method wherein a fluorine-containing polymer is modified by e.g. oxidation, hydrolysis or thermal decomposition.
However, with respect to ETFE, the above method (1) is not effective, since, as mentioned above, the fluorine-containing polymer and the non-fluorine type thermoplastic polymer having a functional group, have no compatibility. The above method (2) is expensive and not practical, since the monomer useful for the copolymerization reaction is very limited. The above method (3) can not be adopted since the fluorine-containing polymer usually has no reactive group. In the above method (4), the fluorine-containing polymer is so stable that it is impossible to form carboxyl groups, hydroxyl groups or epoxy groups by e.g. oxidation, hydrolysis or thermal decomposition.
On the other hand, a thermoplastic composition obtained by blending a fluorine-containing polymer, PPS and an aminoalkoxysilane, has been proposed (JP-A-8-53592). This composition has a part of mechanical properties improved, but it is not disclosed and unclear whether it is in a form of a polymer alloy having a good dispersed state. Further, with respect to ETFE, it is disclosed to use Afron COP C-88A grade in Examples. However, the present inventors have found that from ETFE of such a grade and PPS, it is impossible to obtain a polymer alloy having stable mechanical properties in a good dispersed state even in the presence of an aminoalkoxysilane.